refactor(form-builder): strict validator + drop form_fields.conditional_logic JSON column

WS-5c commit 3 of 4. FormRequests (Store/Update) now reject bad
conditional_logic trees at the HTTP boundary — the `after()` hook
unwraps the `show_when` envelope, normalises legacy `{all|any: [...]}`
group shape to the service's internal form, and delegates to
`FormFieldConditionalLogicService::assertSpecsValid()`. Unknown
operators, root conditions, empty groups, and unknown field_slug
references produce a 422 with a readable error before any write.

`form_fields.conditional_logic` JSON column dropped. FormField model
`$fillable` and `$casts` no longer mention the column; factory default
no longer writes `null` to it. Snapshot fixtures in the dev seeder and
the legacy-forms migration command keep `conditional_logic` in their
snapshot JSON shape — that's the schema_snapshot contract, not the DB
column.

FormFieldController now maps InvalidConditionalLogicSpecException to
422 alongside FrozenSchemaException / CyclicDependencyException.

Rollback path: roll back WS-5c commits 1–3 together. Partial rollback
(drop-column reversed but backfill still applied) is not a supported
state — matching the WS-5a/b precedent on the family's full-rollback
contract.

Tests: 6 new (strict FormRequest rejection cases + JSON-column drop
assertion). Rollback step counts in WS-5a/b migration tests bumped +1
for the drop_conditional_logic_json_column migration. Baseline
1142 → 1148 green (3085 → 3099 assertions).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

api/tests/Feature/FormBuilder/ConditionalLogic/ConditionalLogicBackfillTest.php

@@ -32,7 +32,7 @@ final class ConditionalLogicBackfillTest extends TestCase
     public function test_forward_backfill_builds_nested_tree_from_legacy_json(): void
     {
         // Roll back only the backfill migration (latest WS-5c step).
-        $this->artisan('migrate:rollback', ['--step' => 1])->assertSuccessful();
+        $this->artisan('migrate:rollback', ['--step' => 2])->assertSuccessful();
         $this->assertTrue(Schema::hasColumn('form_fields', 'conditional_logic'));
 
         $fieldId = $this->seedFieldWithJson([
@@ -90,9 +90,11 @@ final class ConditionalLogicBackfillTest extends TestCase
 
     public function test_rollback_reconstructs_canonical_json(): void
     {
-        // Starting state: fully migrated. Seed relational rows bypassing the
-        // service, then roll back one step (backfill) — it should repopulate
-        // the JSON column.
+        // Starting state: fully migrated. The conditional_logic column is
+        // already gone (WS-5c commit 3 drop). Seed relational rows bypassing
+        // the service, then roll back two steps — drop-column reverses first
+        // (column re-appears), then the backfill's `down()` reads relational
+        // rows and writes the JSON back.
         $org = Organisation::factory()->create();
         $schema = FormSchema::factory()->create(['organisation_id' => $org->id]);
 
@@ -105,7 +107,6 @@ final class ConditionalLogicBackfillTest extends TestCase
             'label' => 'Subject',
             'value_storage_hint' => 'json',
             'sort_order' => 0,
-            'conditional_logic' => null,
             'created_at' => now(),
             'updated_at' => now(),
         ]);
@@ -152,7 +153,7 @@ final class ConditionalLogicBackfillTest extends TestCase
         ]);
 
         // Roll back only the backfill migration — writes the JSON back.
-        $this->artisan('migrate:rollback', ['--step' => 1])->assertSuccessful();
+        $this->artisan('migrate:rollback', ['--step' => 2])->assertSuccessful();
 
         $reconstructed = DB::table('form_fields')
             ->where('id', $fieldId)
@@ -179,7 +180,7 @@ final class ConditionalLogicBackfillTest extends TestCase
 
     public function test_unknown_top_level_key_fails_migration(): void
     {
-        $this->artisan('migrate:rollback', ['--step' => 1])->assertSuccessful();
+        $this->artisan('migrate:rollback', ['--step' => 2])->assertSuccessful();
 
         $this->seedFieldWithJson([
             'hide_when' => ['all' => [['field_slug' => 'x', 'operator' => 'equals', 'value' => 1]]],
@@ -192,7 +193,7 @@ final class ConditionalLogicBackfillTest extends TestCase
 
     public function test_unknown_comparison_operator_fails_migration(): void
     {
-        $this->artisan('migrate:rollback', ['--step' => 1])->assertSuccessful();
+        $this->artisan('migrate:rollback', ['--step' => 2])->assertSuccessful();
 
         $this->seedFieldWithJson([
             'show_when' => ['all' => [['field_slug' => 'x', 'operator' => 'matches_regex', 'value' => 'y']]],

api/tests/Feature/FormBuilder/ConditionalLogic/ConditionalLogicJsonColumnDroppedTest.php

@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Feature\FormBuilder\ConditionalLogic;
+
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Illuminate\Support\Facades\Schema;
+use Tests\TestCase;
+
+/**
+ * WS-5c commit 3 — `form_fields.conditional_logic` is gone after the full
+ * migration. Per addendum Q3, no library mirror to check.
+ */
+final class ConditionalLogicJsonColumnDroppedTest extends TestCase
+{
+    use RefreshDatabase;
+
+    public function test_form_fields_conditional_logic_column_is_dropped(): void
+    {
+        $this->assertFalse(
+            Schema::hasColumn('form_fields', 'conditional_logic'),
+            'WS-5c commit 3 must drop form_fields.conditional_logic — it now lives in the relational tree.',
+        );
+    }
+}

api/tests/Feature/FormBuilder/ConditionalLogic/FormFieldStrictConditionalLogicRequestTest.php

@@ -0,0 +1,166 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Feature\FormBuilder\ConditionalLogic;
+
+use App\Enums\FormBuilder\FormFieldType;
+use App\Models\FormBuilder\FormField;
+use App\Models\FormBuilder\FormSchema;
+use App\Models\Organisation;
+use App\Models\User;
+use Database\Seeders\RoleSeeder;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Laravel\Sanctum\Sanctum;
+use Tests\TestCase;
+
+/**
+ * WS-5c commit 3 — strict validator on save. The Store/Update
+ * FormRequests' `after()` hook delegates to
+ * `FormFieldConditionalLogicService::assertSpecsValid`, so bad specs
+ * fail at the HTTP boundary before any write lands.
+ */
+final class FormFieldStrictConditionalLogicRequestTest extends TestCase
+{
+    use RefreshDatabase;
+
+    private Organisation $org;
+
+    private User $admin;
+
+    private FormSchema $schema;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->seed(RoleSeeder::class);
+        $this->org = Organisation::factory()->create();
+        $this->admin = User::factory()->create();
+        $this->org->users()->attach($this->admin, ['role' => 'org_admin']);
+        $this->schema = FormSchema::factory()->create(['organisation_id' => $this->org->id]);
+    }
+
+    public function test_store_rejects_unknown_comparison_operator(): void
+    {
+        Sanctum::actingAs($this->admin);
+
+        FormField::factory()->create(['form_schema_id' => $this->schema->id, 'slug' => 'gate']);
+
+        $response = $this->postJson(
+            "/api/v1/organisations/{$this->org->id}/forms/schemas/{$this->schema->id}/fields",
+            [
+                'field_type' => FormFieldType::TEXT->value,
+                'slug' => 'target',
+                'label' => 'Target',
+                'conditional_logic' => [
+                    'show_when' => [
+                        'all' => [
+                            ['field_slug' => 'gate', 'operator' => 'matches_regex', 'value' => 'y'],
+                        ],
+                    ],
+                ],
+            ],
+        );
+
+        $response->assertStatus(422);
+        $response->assertJsonValidationErrors(['conditional_logic']);
+    }
+
+    public function test_store_rejects_root_condition_without_group(): void
+    {
+        Sanctum::actingAs($this->admin);
+
+        $response = $this->postJson(
+            "/api/v1/organisations/{$this->org->id}/forms/schemas/{$this->schema->id}/fields",
+            [
+                'field_type' => FormFieldType::TEXT->value,
+                'slug' => 'target',
+                'label' => 'Target',
+                // Condition at root — invalid; ARCH §8 requires a group wrapper.
+                'conditional_logic' => [
+                    'show_when' => [
+                        'field_slug' => 'gate',
+                        'operator' => 'equals',
+                        'value' => 'y',
+                    ],
+                ],
+            ],
+        );
+
+        $response->assertStatus(422);
+        $response->assertJsonValidationErrors(['conditional_logic']);
+    }
+
+    public function test_store_rejects_empty_group(): void
+    {
+        Sanctum::actingAs($this->admin);
+
+        $response = $this->postJson(
+            "/api/v1/organisations/{$this->org->id}/forms/schemas/{$this->schema->id}/fields",
+            [
+                'field_type' => FormFieldType::TEXT->value,
+                'slug' => 'target',
+                'label' => 'Target',
+                'conditional_logic' => ['show_when' => ['all' => []]],
+            ],
+        );
+
+        $response->assertStatus(422);
+        $response->assertJsonValidationErrors(['conditional_logic']);
+    }
+
+    public function test_store_rejects_unknown_field_slug(): void
+    {
+        Sanctum::actingAs($this->admin);
+
+        $response = $this->postJson(
+            "/api/v1/organisations/{$this->org->id}/forms/schemas/{$this->schema->id}/fields",
+            [
+                'field_type' => FormFieldType::TEXT->value,
+                'slug' => 'target',
+                'label' => 'Target',
+                'conditional_logic' => [
+                    'show_when' => [
+                        'all' => [
+                            ['field_slug' => 'nonexistent', 'operator' => 'equals', 'value' => 'y'],
+                        ],
+                    ],
+                ],
+            ],
+        );
+
+        $response->assertStatus(422);
+        $this->assertStringContainsString('nonexistent', (string) $response->json('message'));
+    }
+
+    public function test_store_accepts_valid_tree_and_persists_relational_rows(): void
+    {
+        Sanctum::actingAs($this->admin);
+        FormField::factory()->create(['form_schema_id' => $this->schema->id, 'slug' => 'gate']);
+
+        $response = $this->postJson(
+            "/api/v1/organisations/{$this->org->id}/forms/schemas/{$this->schema->id}/fields",
+            [
+                'field_type' => FormFieldType::TEXT->value,
+                'slug' => 'target',
+                'label' => 'Target',
+                'conditional_logic' => [
+                    'show_when' => [
+                        'all' => [
+                            ['field_slug' => 'gate', 'operator' => 'equals', 'value' => 'yes'],
+                        ],
+                    ],
+                ],
+            ],
+        );
+
+        $response->assertStatus(201);
+        $this->assertSame([
+            'show_when' => [
+                'all' => [
+                    ['field_slug' => 'gate', 'operator' => 'equals', 'value' => 'yes'],
+                ],
+            ],
+        ], $response->json('data.conditional_logic'));
+    }
+}